Onboard the ship you will pay whatever the current International Data Rate is for the cruise line. You can connect via Wi-fi (802.11bgn) and pay anywhere from .50 to .35/minute. It's less if you buy a package for Internet access.
Voice calls are going to be $2.49/minute and data is $20.48/MB.
Check with Verizon and their International Data Plan. It runs around $25/month for 100MB of data. If you go over 100MB you will be charged $25 for 100MB more of data. Each time you go over your allotment then an additional 100MB of data and $25 is added to your account. Also: You receive a text message that you are approaching your limit. It is a pretty good deal since "Pay as you go", on the ship is around $20/MB Ouch
Many people have come home to bills well $1000 because they thought the voice/text/data they were using was included in their plan.
__________________ Cruisemates Community Leader/Moderator
"There is a great difference between being well traveled and just having been to many places." ~Me